Tumour morphology as a predictor of outcome after local excision of rectal cancer

Background: The aim of this study was to determine whether the morphology of rectal cancer predicts outcome following treatment by local excision, and whether morphology should therefore be added to the criteria presently used for case selection. Methods: The hospital notes and histological findings of 91 patients who had undergone a local surgical procedure for rectal cancer were reviewed retrospectively. Eight patient and tumour characteristics including morphology were analysed with respect to 5-year survival, local recurrence and cancer-specific death within 5 years. Morphology was divided into four types: polypoid, sessile, ulcerated and flat raised. Results: Survival and local recurrence were significantly better for patients with exophytic (polypoid and sessile) carcinomas than for those with non-exophytic (ulcerated and flat raised) lesions. Multivairiate logistic regression analysis showed that age, depth of invasion, lymphatic invasion and venous invasion were significant predictors of outcome. The exophytic group included significantly more stage T1 and fewer T2 and T3 cancers, and a significantly smaller proportion of tumours that showed venous and lymphatic invasion than the non-exophytic group. Conclusion: Morphology is a clinical guide to prognosis after local excision. Non-exophytic cancers-are associated with high-risk histopathological features that render tumours of this type unsuitable for local excision.